service/pipewire: add a way to set preferred default nodes

src/services/pipewire/defaults.cpp

@@ -2,9 +2,12 @@
 #include <array>
 #include <cstring>
 
+#include <qjsondocument.h>
+#include <qjsonobject.h>
 #include <qlogging.h>
 #include <qloggingcategory.h>
 #include <qobject.h>
+#include <qstringview.h>
 #include <qtmetamacros.h>
 #include <spa/utils/json.h>
 
@@ -63,7 +66,7 @@ void PwDefaultTracker::onMetadataProperty(const char* key, const char* type, con
 	} else return;
 
 	QString name;
-	if (strcmp(type, "Spa:String:JSON") == 0) {
+	if (type != nullptr && value != nullptr && strcmp(type, "Spa:String:JSON") == 0) {
 		auto failed = true;
 		auto iter = std::array<spa_json, 2>();
 		spa_json_init(&iter[0], value, strlen(value));
@@ -138,6 +141,70 @@ void PwDefaultTracker::onNodeDestroyed(QObject* node) {
 	}
 }
 
+void PwDefaultTracker::changeConfiguredSink(PwNode* node) {
+	if (node != nullptr) {
+		if (!node->isSink) {
+			qCCritical(logDefaults) << "Cannot change default sink to a node that is not a sink.";
+			return;
+		}
+
+		this->changeConfiguredSinkName(node->name);
+	} else {
+		this->changeConfiguredSinkName("");
+	}
+}
+
+void PwDefaultTracker::changeConfiguredSinkName(const QString& sink) {
+	if (sink == this->mDefaultConfiguredSinkName) return;
+
+	if (this->setConfiguredDefault("default.configured.audio.sink", sink)) {
+		this->mDefaultConfiguredSinkName = sink;
+		qCInfo(logDefaults) << "Set default configured sink to" << sink;
+	}
+}
+
+void PwDefaultTracker::changeConfiguredSource(PwNode* node) {
+	if (node != nullptr) {
+		if (node->isSink) {
+			qCCritical(logDefaults) << "Cannot change default source to a node that is not a source.";
+			return;
+		}
+
+		this->changeConfiguredSourceName(node->name);
+	} else {
+		this->changeConfiguredSourceName("");
+	}
+}
+
+void PwDefaultTracker::changeConfiguredSourceName(const QString& source) {
+	if (source == this->mDefaultConfiguredSourceName) return;
+
+	if (this->setConfiguredDefault("default.configured.audio.source", source)) {
+		this->mDefaultConfiguredSourceName = source;
+		qCInfo(logDefaults) << "Set default configured source to" << source;
+	}
+}
+
+bool PwDefaultTracker::setConfiguredDefault(const char* key, const QString& value) {
+	auto* meta = this->defaultsMetadata.object();
+
+	if (!meta || !meta->proxy()) {
+		qCCritical(logDefaults) << "Cannot set default node as metadata is not ready.";
+		return false;
+	}
+
+	if (value.isEmpty()) {
+		meta->setProperty(key, "Spa:String:JSON", nullptr);
+	} else {
+		// Spa json is a superset of json so we can avoid the awful spa json api when serializing.
+		auto json = QJsonDocument({{"name", value}}).toJson(QJsonDocument::Compact);
+
+		meta->setProperty(key, "Spa:String:JSON", json.toStdString().c_str());
+	}
+
+	return true;
+}
+
 void PwDefaultTracker::setDefaultSink(PwNode* node) {
 	if (node == this->mDefaultSink) return;
 	qCInfo(logDefaults) << "Default sink changed to" << node;

src/services/pipewire/defaults.hpp

@@ -18,9 +18,13 @@ public:
 
 	[[nodiscard]] PwNode* defaultConfiguredSink() const;
 	[[nodiscard]] const QString& defaultConfiguredSinkName() const;
+	void changeConfiguredSink(PwNode* node);
+	void changeConfiguredSinkName(const QString& sink);
 
 	[[nodiscard]] PwNode* defaultConfiguredSource() const;
 	[[nodiscard]] const QString& defaultConfiguredSourceName() const;
+	void changeConfiguredSource(PwNode* node);
+	void changeConfiguredSourceName(const QString& source);
 
 signals:
 	void defaultSinkChanged();
@@ -54,6 +58,8 @@ private:
 	void setDefaultConfiguredSource(PwNode* node);
 	void setDefaultConfiguredSourceName(const QString& name);
 
+	bool setConfiguredDefault(const char* key, const QString& value);
+
 	PwRegistry* registry;
 	PwBindableRef<PwMetadata> defaultsMetadata;
 

src/services/pipewire/qml.cpp

@@ -143,11 +143,19 @@ PwNodeIface* Pipewire::defaultConfiguredAudioSink() const { // NOLINT
 	return PwNodeIface::instance(node);
 }
 
+void Pipewire::setDefaultConfiguredAudioSink(PwNodeIface* node) {
+	PwConnection::instance()->defaults.changeConfiguredSink(node ? node->node() : nullptr);
+}
+
 PwNodeIface* Pipewire::defaultConfiguredAudioSource() const { // NOLINT
 	auto* node = PwConnection::instance()->defaults.defaultConfiguredSource();
 	return PwNodeIface::instance(node);
 }
 
+void Pipewire::setDefaultConfiguredAudioSource(PwNodeIface* node) {
+	PwConnection::instance()->defaults.changeConfiguredSource(node ? node->node() : nullptr);
+}
+
 PwNodeIface* PwNodeLinkTracker::node() const { return this->mNode; }
 
 void PwNodeLinkTracker::setNode(PwNodeIface* node) {

src/services/pipewire/qml.hpp

@@ -60,28 +60,38 @@ class Pipewire: public QObject {
 	Q_PROPERTY(ObjectModel<PwLinkGroupIface>* linkGroups READ linkGroups CONSTANT);
 	/// The default audio sink (output) or `null`.
 	///
+	/// This is the default sink currently in use by pipewire, and the one applications
+	/// are currently using.
+	///
+	/// To set the default sink, use @@preferredDefaultAudioSink.
+	///
 	/// > [!INFO] When the default sink changes, this property may breifly become null.
 	/// > This depends on your hardware.
 	Q_PROPERTY(PwNodeIface* defaultAudioSink READ defaultAudioSink NOTIFY defaultAudioSinkChanged);
 	/// The default audio source (input) or `null`.
 	///
+	/// This is the default source currently in use by pipewire, and the one applications
+	/// are currently using.
+	///
+	/// To set the default source, use @@preferredDefaultAudioSource.
+	///
 	/// > [!INFO] When the default source changes, this property may breifly become null.
 	/// > This depends on your hardware.
 	Q_PROPERTY(PwNodeIface* defaultAudioSource READ defaultAudioSource NOTIFY defaultAudioSourceChanged);
-	/// The configured default audio sink (output) or `null`.
+	/// The preferred default audio sink (output) or `null`.
 	///
-	/// This is not the same as @@defaultAudioSink. While @@defaultAudioSink is the
-	/// sink that will be used by applications, @@defaultConfiguredAudioSink is the
-	/// sink requested to be the default by quickshell or another configuration tool,
-	/// which might not exist or be valid.
-	Q_PROPERTY(PwNodeIface* defaultConfiguredAudioSink READ defaultConfiguredAudioSink NOTIFY defaultConfiguredAudioSinkChanged);
-	/// The configured default audio source (input) or `null`.
+	/// This is a hint to pipewire telling it which sink should be the default when possible.
+	/// @@defaultAudioSink may differ when it is not possible for pipewire to pick this node.
 	///
-	/// This is not the same as @@defaultAudioSource. While @@defaultAudioSource is the
-	/// source that will be used by applications, @@defaultConfiguredAudioSource is the
-	/// source requested to be the default by quickshell or another configuration tool,
-	/// which might not exist or be valid.
-	Q_PROPERTY(PwNodeIface* defaultConfiguredAudioSource READ defaultConfiguredAudioSource NOTIFY defaultConfiguredAudioSourceChanged);
+	/// See @@defaultAudioSink for the current default sink, regardless of preference.
+	Q_PROPERTY(PwNodeIface* preferredDefaultAudioSink READ defaultConfiguredAudioSink WRITE setDefaultConfiguredAudioSink NOTIFY defaultConfiguredAudioSinkChanged);
+	/// The preferred default audio source (input) or `null`.
+	///
+	/// This is a hint to pipewire telling it which source should be the default when possible.
+	/// @@defaultAudioSource may differ when it is not possible for pipewire to pick this node.
+	///
+	/// See @@defaultAudioSource for the current default source, regardless of preference.
+	Q_PROPERTY(PwNodeIface* preferredDefaultAudioSource READ defaultConfiguredAudioSource WRITE setDefaultConfiguredAudioSource NOTIFY defaultConfiguredAudioSourceChanged);
 	// clang-format on
 	QML_ELEMENT;
 	QML_SINGLETON;
@@ -97,7 +107,10 @@ public:
 	[[nodiscard]] PwNodeIface* defaultAudioSource() const;
 
 	[[nodiscard]] PwNodeIface* defaultConfiguredAudioSink() const;
+	static void setDefaultConfiguredAudioSink(PwNodeIface* node);
+
 	[[nodiscard]] PwNodeIface* defaultConfiguredAudioSource() const;
+	static void setDefaultConfiguredAudioSource(PwNodeIface* node);
 
 signals:
 	void defaultAudioSinkChanged();